Liquid Crystal Display (LCD) devices have become mainstream products among current flat panel display devices because of small size, low power consumption and no radiation. A liquid crystal display panel is a key component in a liquid crystal display device, and a liquid crystal display panel includes a paired array substrate and a color film substrate, as well as a liquid crystal layer arranged between the array substrate and the color film substrate.
In order to make liquid crystals in the liquid crystal display panel keep a specific alignment when having no power, alignment layers are to be formed on the surfaces of the array substrate and of the color film substrate, wherein the surfaces are facing to each other. Grooves with specific alignment are formed on the alignment layers and the grooves are usually formed by the rubbing of rubbing cloth.
In the rubbing process to form the alignment layer of the array substrate, Rubbing Mura (also known as rubbing marks, which refer to bad consistency of grooves in the alignment layer formed by using rubbing cloth to rub the surface of the array substrate, i.e., inconsistency of groove alignments of the alignment layer) is often easily generated, and seriously affects the display quality of the liquid crystal display panel.
Through tests, it is found that the Rubbing Mura is not caused by the rubbing cloth, but is caused by the wiring design of the peripheral circuit of the array substrate. Test electrodes, for testing whether a test display panel is normal or good, are usually laid out in non-display regions of the array substrate, and the test electrodes are used to transmit a test signal into the inside of the display panel to perform the test. In order for the smooth transmission of the test signal, the test electrodes are usually designed as a bulk with larger area, while peripheral wiring of the test electrodes is usually designed as thinner line-shape, which leads to certain surface morphology differences of the test electrode and its peripheral wiring.
In the process of performing rubbing alignment with rubbing cloth, the rubbing cloth usually starts rubbing from a side of the array substrate until rubbing to the relative other side of the array substrate, and since the surface morphology of the bulk test electrodes is greatly different from the surface morphology of its peripheral line wiring, the cloth hair alignment of the rubbing cloth is chaotic (i.e., inconsistent alignment), thereby leading to inconsistency of alignment of grooves formed by the rubbing when the rubbing cloth enters a display region from a non-display region, that is, Rubbing Mura is easily generated and seriously affects the imaging quality of the liquid crystal display panel.